In this proposal, we propose to combine (a) the latest protein engineering techniques with (b) stimuli-responsive polymer compositions to produce (c) responsive polymer-engineered protein (RP-EP) conjugates that have unique behaviors and uses. More specifically, we propose to conjugate temperature-, pH- or light-sensitive oligomers by one of their terminal ends to a specific site near or within the active recognition site of selected proteins, and then to apply a temperature, pH or light stimulus to tern " (i.e., allow binding) or "off" (i.e., either reduce the binding affinity, prevent binding altogether, or eject a previously-bound receptor) the binding of the target ligand or cell to the proteins's recognition site. The protein could be an antibody, an enzyme, a hormone, an integrin, albumin, streptavidin, or any other recognition protein. The protein could be an antibody, an enzyme, a hormone, an integrin, albumin, streptavidin, or any other recognition protein. The ability to turn on or off biological recognition processes on a molecular level should lead to many interesting, diverse and unique applications. In this proposal we focus on the affinity recognition process, and its applications in affinity separations, diagnostics and biosensors.